The present invention relates generally to the implant of prosthetic devices at various joints in the body and pertains, more specifically, to method and apparatus for preparing the bone at the joint for receiving a component part or parts of the prosthetic device to be implanted.
The use of prosthetic devices to replace damaged natural joints, or portions of such joints, in the body has become widespread as medical and technological advances have joined to provide improved materials and configurations for prosthetic devices and innovative procedures for implanting these devices. The basic objective of such devices and procedures, of course, is to provide a repaired joint of maximum effectiveness, with a minimal intrusion into the body of the recipient of the device. Component parts of the prosthetic device are utilized to replace portions of a natural joint which have become damaged, either through injury or disease, and it is usually necessary to remove portions of the natural joint beyond merely the damaged portions in order to enable stable and secure affixation of the component parts to the natural bone. In addition, access to damaged joints is limited and the necessity for reaching the areas to be worked upon can affect the extent of intrusion required to complete an effective implant.
Among the objects and advantages of the present invention in providing an improved method and apparatus by which a prosthetic device may be implanted at the joint of a body are those which are summarized as follows: Requires removal of only a minimal amount of the natural bone at the joint, consistent with enabling stable and secure affixation of each component part of the prosthetic device; attains accuracy in the delineation of the area, depth and contour configuration of the prepared surfaces of the bone which. will receive a component part of the prosthetic implant; enables such accuracy within the confines of the limited access available at the joint, with minimal disturbance of surrounding tissue in the vicinity of the joint; allows the use of a minimum number of instruments and steps of limited complexity in carrying out the procedure; provides the ability to use currently available instruments in connection with elements of the present apparatus and current techniques in connection with the steps of the present method for compatibility and widespread acceptance among surgeons; allows a certain amount of discretion on the part of the surgeon in accommodating particular conditions encountered at an implant site, while preserving ease and accuracy in completing preparation of the site for the implant.
The above objects and advantages, as well as further objects and advantages, are attained by the present invention which may be described briefly as apparatus for preparing a seating surface of prescribed depth, contour configuration and area delineated by a prescribed peripheral boundary extending along the bone of a natural joint at which a prosthetic device is to be implanted, the bone having been provided with at least a partially prepared site for locating and seating a component part of the prosthetic device at the seating surface, the apparatus comprising: a depth, contouring and area guide block having longitudinally opposite first and second ends, laterally opposite first and second sides, an upper locator surface and a lower guide locating surface; at least a portion of the upper locator surface having a profile contour configuration essentially matching a corresponding portion of the contour configuration of the seating surface; a holding arrangement integral with the guide block for holding the guide block on the bone at the site with the guide block placed at a predetermined location and orientation relative to the bone; a guide slot passing altitudinally through the guide block from the upper locator surface to the lower guide locating surface, the guide slot having a length, a laterally outer locator edge extending along a path geometrically similar to the peripheral boundary of the seating surface, a laterally inner edge and a lateral width between the outer locator edge and the inner edge; and a cutting device for reception within the guide slot, the cutting device having a cutting axis for extending altitudinally when the cutting device is received within the guide slot, an axial cutting surface for rotation about the cutting axis, the axial cutting surface having a near end and a far end, a radial cutting surface transverse to the axial cutting surface at the far end, a radial bearing surface located at a predetermined axial distance from the radial cutting surface, and an axial bearing surface located axially between the radial bearing surface and the near end of the axial cutting surface; the axial cutting surface having a diameter less than the lateral width of the guide slot, the axial bearing surface having a diameter less than the lateral width of the guide slot, and the radial bearing surface having a diameter greater than the lateral width of the guide slot, the diameters of the axial cutting surface, the axial bearing surface and the radial bearing surface having relative dimensions such that upon reception of the cutting device within the guide slot, the cutting device is capable of insertion axially into the guide slot in an altitudinal direction at any selected location along the length of the guide slot, the axial bearing surface follows the contour configuration of the outer locator edge of the guide slot to locate the axial cutting surface along the peripheral boundary of the seating surface while the radial bearing surface follows the upper locator surface, with the radial bearing surface overlying the outer locator edge and the inner edge of the guide slot to stabilize and locate the radial cutting surface at the prescribed depth of the seating surface.
The invention further includes an improvement in an apparatus for preparing a seating surface of prescribed depth, contour and area placed within a prescribed peripheral boundary extending along the bone of a natural joint at which a prosthetic device is to be implanted, the bone having been provided with at least a partially prepared site for locating and seating a component part of the prosthetic device at the seating surface, the apparatus including a depth, contouring and area guide for guiding a cutting device to be received within the guide, the cutting device having a cutting axis for extending altitudinally within the guide, an axial cutting surface for rotation about the cutting axis, the axial cutting surface having a first diameter, a near end and a far end, a radial cutting surface transverse to the axial cutting surface at the far end, a radial bearing surface having a second diameter and being located at a predetermined axial distance from the radial cutting surface, and an axial bearing surface having a third diameter and being located axially between the radial bearing surface and the near end of the axial cutting surface, the improvement comprising: a depth, contouring and area guide block having longitudinally opposite first and second ends, laterally opposite first and second sides, an upper locator surface and a lower guide locating surface; at least a portion of the upper locator surface having a profile contour configuration essentially matching a corresponding portion of the contour configuration of the seating surface; a holding arrangement integral with the guide block for holding the guide block on the bone at the site with the guide block placed at a predetermined location and orientation relative to the bone; and a guide slot extending altitudinally through the guide block from the upper locator surface to the lower guide locating surface, the guide slot having a length, a laterally outer locator edge following a path geometrically similar to the peripheral boundary of the seating surface, a laterally inner edge and a lateral width between the outer locator edge and the inner edge; the lateral width of the guide slot being greater than each of the first and third diameters and less than the second diameter with the first, second and third diameters having relative dimensions such that upon reception of the cutting device within the guide slot, the cutting device is capable of insertion axially into the guide slot in an altitudinal direction at any selected location along the length of the guide slot, the axial bearing surface follows the outer locator edge of the guide slot to locate the axial cutting surface along the peripheral boundary of the seating surface while the radial bearing surface follows the upper locator surface, with the radial bearing surface overlying the outer locator edge and the inner edge of the guide slot to stabilize and locate the radial cutting surface at the prescribed depth of the seating surface.
Still further, the invention includes an improvement in an apparatus for preparing a seating surface of prescribed depth, contour and area delineated by a prescribed peripheral boundary extending along the bone of a natural joint at which a prosthetic device is to be implanted, the bone having been provided with at least a partially prepared site for locating and seating a component part of the prosthetic device at the seating surface, the apparatus including a depth, contouring and area guide block having longitudinally opposite first and second ends, laterally opposite first and second sides, an upper locator surface and a lower guide locating surface, at least a portion of the upper locator surface having a profile contour configuration essentially matching a corresponding portion of the contour configuration of the seating surface, a holding arrangement integral with the guide block for holding the guide block on the bone at the site with the guide block placed at a predetermined location and orientation relative to the bone, a guide slot extending altitudinally through the guide block from the upper locator surface to the lower guide locating surface, the guide slot having a length, a laterally outer locator edge following a path geometrically similar to the peripheral boundary of the seating surface, a laterally inner edge and a lateral width between the outer locator edge and the inner edge, the improvement comprising: a cutting device for reception within the guide slot, the cutting device including a cutting axis for extending altitudinally when the cutting device is received within the guide slot; an axial cutting surface for rotation about the cutting axis, the axial cutting surface having a near end and a far end; a radial cutting surface transverse to the axial cutting surface at the far end; a radial bearing surface located at a predetermined axial distance from the radial cutting surface; and an axial bearing surface located axially between the radial bearing surface and the near end of the axial cutting surface; the axial cutting surface having a diameter less than the lateral width of the guide slot, the axial bearing surface having a diameter less than the lateral width of the guide slot, and the radial bearing surface having a diameter greater than the lateral width of the guide slot, the diameters of the axial cutting surface, the axial bearing surface and the radial bearing surface having relative dimensions such that upon reception of the cutting device within the guide slot, the cutting device is capable of insertion axially into the guide slot in an altitudinal direction at any selected location along the length of the guide slot, the axial bearing surface follows the outer locator edge of the guide slot to locate the axial cutting surface along the peripheral boundary of the seating surface while the radial bearing surface follows the upper locator surface, with the radial bearing surface overlying the outer locator edge and the inner edge of the guide slot to stabilize and locate the radial cutting surface at the prescribed depth of the seating surface.
In addition, the invention includes a method of preparing a seating surface of prescribed depth, contour and area delineated by a prescribed peripheral boundary extending along the bone of a natural joint at which a prosthetic device is to be implanted, the bone having been provided with at least a partially prepared site for locating and seating a component part of the prosthetic device at the seating surface, the method comprising the steps of: positioning a depth, contouring and area guide on the bone at the site, the guide including a guide slot having a length following a path geometrically similar to the peripheral boundary of the seating surface, the length including longitudinal length portions spaced apart laterally; engaging a cutting device with the guide by inserting the cutting device altitudinally through the guide slot at any selected location along the path of the guide slot; translating the cutting device along the length of the guide slot to cut an outline groove in the bone coincident with the peripheral boundary of the seating surface such that the outline groove establishes an outline contiguous with the area of the seating surface; removing the guide from the bone subsequent to translating the cutting device along the length of the guide slot; and removing portions of the bone lying within the area contiguous with and delineated by the outline groove to establish the seating surface.